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  • AC自动机 HDU 2222 Keywords Search

    Problem Description
    In the modern time, Search engine came into the life of everybody like Google, Baidu, etc.
    Wiskey also wants to bring this feature to his image retrieval system.
    Every image have a long description, when users type some keywords to find the image, the system will match the keywords with description of image and show the image which the most keywords be matched.
    To simplify the problem, giving you a description of image, and some keywords, you should tell me how many keywords will be match.
     
    Input
    First line will contain one integer means how many cases will follow by.
    Each case will contain two integers N means the number of keywords and N keywords follow. (N <= 10000)
    Each keyword will only contains characters 'a'-'z', and the length will be not longer than 50.
    The last line is the description, and the length will be not longer than 1000000.
     
    Output
    Print how many keywords are contained in the description.
     
    Sample Input
    1 5 she he say shr her yasherhs
     
    Sample Output
    3
     
     
                         http://yzmduncan.iteye.com/blog/1217014
     
    模板:
    View Code
     1 #include <stdio.h>
     2 #include <stdlib.h>
     3 
     4 int const N= 500010;
     5 struct Trie{
     6     int flag;  // 标记是否为某一模式串的结尾 
     7     int fail;  // 失败指针 
     8     int next[26];
     9     void init(){
    10         flag= 0; fail= -1;
    11         for( int i= 0; i< 26; ++i ) next[i]= 0; }
    12 }tb[N];
    13 
    14 int cnt= 0, que[N], n;
    15 char str[1000010];
    16 
    17 void inline insert( char* s ){
    18     int rt= 0;
    19     while( *s ){
    20         int t= *s- 'a';
    21         if( !tb[rt].next[t] ){
    22             tb[++cnt].init();
    23             tb[rt].next[t]= cnt;
    24         }
    25         rt= tb[rt].next[t]; s++;
    26     }
    27     tb[rt].flag++;
    28 }
    29 
    30 void bfs(){
    31     int head= 0, tail= 0, p, q;
    32     que[0]= 0;
    33     while( head<= tail ){
    34         int now= que[head++];
    35         for( int t= 0; t< 26; ++t )
    36         if( tb[now].next[t] ){
    37             p= tb[now].fail, q= tb[now].next[t];
    38             while( p!= -1 && !tb[p].next[t] ) p= tb[p].fail;
    39             if( p== -1 ) tb[q].fail= 0;
    40             else tb[q].fail= tb[p].next[t];
    41             que[++tail]= q;
    42         }
    43     }
    44 }
    45 
    46 void Match( char* s ){
    47     int ans= 0, rt= 0, t, p;
    48     while( *s ){
    49         t= *s- 'a';
    50         if( tb[rt].next[t] ) rt= tb[rt].next[t];
    51         else{
    52             p= tb[rt].fail;
    53             while( p!= -1 && !tb[p].next[t] ) p= tb[p].fail;
    54             if( p== -1 ) rt= 0;
    55             else rt= tb[p].next[t];
    56         }
    57         p= rt;
    58         while( p!= 0 && tb[p].flag ){
    59             if( tb[p].flag ){
    60                 ans+= tb[p].flag; tb[p].flag= 0; }
    61             p= tb[p].fail;
    62         }
    63         s++;
    64     }
    65     printf("%d\n", ans );
    66 }
    67 
    68 int main(){
    69     int test;
    70     scanf("%d",&test ); 
    71     while( test-- ){
    72         scanf("%d\n",&n ); 
    73         cnt= 0; tb[0].init();
    74         while( n-- ){
    75             gets(str);
    76             insert( str );
    77         }
    78         bfs();
    79         gets(str);
    80         Match( str );
    81     }
    82     
    83     return 0;
    84 }
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    就是一段程序,可以求出N个不等长列表中取N个元素形成的所有组合
  • 原文地址:https://www.cnblogs.com/frog112111/p/2742564.html
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